Recently, along with the electronic devices becoming more compact and highly integrated, a semiconductor chip which is a constitution member of the electronic devices has become thinner. Therefore, the conventional thickness of the wafer was 350 μm or so, however it is demanded to be as thin as 50 to 100 μm, or even thinner than this.
The backside grinding of the wafer after forming the circuit pattern on the semiconductor wafer surface has been done conventionally. Here, the adhesive sheet called surface protective sheet is adhered on the circuit face to protect the circuit face and to fix the wafer, and then the backside grinding is carried out. When grinding, in order to remove the grinding dust and the heat generated, generally water is sprayed to the grinding face of the wafer.
Conventionally, for the surface protective sheet, the adhesive sheet is used which is formed by coating the adhesive agent on the base. The patent document 1 prevents the wafer from curving after the backside grinding by using the surface protective sheet having high stress relaxation rate.